The present invention relates to a door latch actuator disposed in a door latch device of a vehicle to switch a locking mechanism in a door latch device to a lock state and an unlock state.
As described in JP2007-211506A, a conventional door latch actuator comprises a reversible motor; a worm wheel rotated by the motor; a pinion fixed to a rotary shaft of the worm wheel; and an actuating member that actuates a locking mechanism of the door latch device to a lock position for a lock state and an unlock state for an unlock state.
JP2013-217050A discloses an actuator that comprises a reversible motor; a worm wheel rotated by the motor; three teeth equally spaced on a rotary surface of the worm wheel; and a lock lever that comes in contact with any one of the three teeth based on rotation of the worm wheel, wherein the teeth is rotated together with the worm wheel by the motor to rotate the lock lever to a lock position and an unlock position to switch the door latch device to a lock state and an unlock state.
In order to make the actuator in JP2007-211506A smaller and lighter, a drive torque has to become greater and a diameter of the pinion has to be made as small as possible, which increases operation time of the motor for moving the actuating member with the pinion from an unlock position to a lock position and vice versa and increases a rotation angle of the worm wheel driven by the motor and of the pinion. Thus, there is a problem that operation time of the actuator with the motor is long until the door latch device is switched to the lock state and the unlock state.
The actuating member is moved to the lock position and the unlock position by manually operating means such as a knob lever and a key cylinder. Because the pinion always meshes with the actuating member, the worm wheel and the motor rotate together to make a motion of the manually operating means leaden when the actuating member is moved by the manually operating means.
In the actuator in JP2013-217050A, the three teeth are spaced circumferentially by nearly 120 degrees, and each of the teeth is in contact with the lock lever, increasing a rotation angle of the worm wheel for rotating the lock lever to the lock position and the unlock position and thus increasing operation time of the actuator for switching the door latch device to the lock state and the unlock state.